Novel Dilatant Fluids

ABSTRACT

There is provided a novel adhesive shear thickening dilatant fluid and process for the formation thereof comprising the sequential steps of adding to a gel comprising starch and water and adding thereto a sufficient portion of dry solid material, suitably a starch, to form a kneadable solid which is dry to the touch. In particular it is directed to a material whose principle component is uncooked waxy corn starch.

FIELD OF THE INVENTION

Non toxic dilatant compositions based on starch which may be moldedformed and reformed and remain workable for a substantial period oftime.

BACKGROUND OF THE INVENTION

Dilatant compositions made with uncooked finely divided starch suspendedin water are well known. They are often used to demonstrate shearthickening. Their disadvantages are also well known. Principally onceuncooked starch is put into suspension it immediately begins to settleout of suspension. Furthermore once the material is exposed to air itrapidly dries out and can no longer be used. Starch, uncooked, mixedwith water yields a material that is either crumbly or runny. While itmay be dilatant, it is not well suited to being molded.

Over the years many attempts have been made to overcome some of theseproblems but none solve all of the problems associated with them.

While there are a number of more stable shear thickening compositions,many require unusual or synthetic materials. Starch based shearthickening materials provide plant based non toxic compositions. Thereis a need for a more stable starch based material that demonstratesshear thickening.

Materials useful for the purposes of the present invention have been inthe market for many years. Silicone putty (Silly Putty®) is made ofsilicone oil, it is a dilatant, but can NOT be formed and dried, isrelatively expensive and tends to stain objects it contacts, it is NOTbiodegradable, lasts long after it gets dirty, and can NOT be cleaned.

Play doughs (like Play Doh®) are made of wheat (gluten) and/or starchbut are not dilatant. They can be formed and dried and are relativelyinexpensive. They tend to be messy, and are usually biodegradable. Theylast long after they get dirty, and cannot be cleaned.

The product produced by the process of the present invention is made ofstarch, is dilatant and can be formed and dried. It is kneadable,relatively inexpensive, very easy to clean up, and is biodegradable.After use it eventually changes to liquid, becomes crumbly and can bediscarded as it gets dirty. It is not understood why the addition of adry uncooked starch to a gel initially formed from water and starch,suitably, but not limited to dry starch, gives rise to such a product.

The product is significantly more stable than a suspension of uncookedfinely divided starch in a liquid medium such as water. After repeatedsqueezing beyond the kneading of production, the product will begin tobreak down. While the specific mechanism causing this is not wellunderstood, this appears to take the form of water being released fromthe starch gel. Separately, if exposed to the air, water will evaporateand the material will dry and become solid

After the material becomes more fluid it is still fun to play with,though somewhat more messy. As the material is used, it naturallycollects dust and dirt, as well as other residues from hands or surfacesin contact with the material. Eventually it is discarded, and isbiodegradable.

DISCUSSION OF THE PRIOR ART

U.S. Pat. No. 3,167,440 discloses a pliable craft modeling compositionmade of starch (as “wheat flour”) in water, and including salt andborax.

U.S. Pat. No. 4,375,535 discloses using high amylopectin starch in achemically modified composition to make an aqueous dispersion that doesnot thicken. This document appears to provide some relevant details ofthe physical and chemical behavior of amylopectin in various chemicalmedia and conditions.

U.S. Pat. No. 5,362,777 discloses a “thermo plastically processablestarch” in which a gum (i.e. polysaccharide) involving saccharide unitsis used in addition to an already dispersed starch in an aqueoussolution. Products made with this composition include extruded tubes.

U.S. Pat. No. 5,614,243 discloses a food formulation includingpregelatinized starch and an insoluble ingredient (e.g., TiO₂), in orderto provide a texturized product.

U.S. Pat. No. 6,713,624 discloses a starch-based modeling compoundincluding a starch-based binder and 2-10% of a “retrogradationinhibitor,” such as a waxy corn starch. The invention of the presentapplication is distinguishable from Hasbro U.S. Pat. No. 6,713,624 bothin that the present invention has a suspended uncooked starch component,and exhibits shear thickening properties.

U.S. Pat. No. 6,713,624 material lacks a suspended uncooked starchcomponent, and exhibits shear thinning properties like many play doughs.

U.S. Pat. No. 7,861,637 discloses a “pressure impulse mitigation”structure, e.g., a body armor, including a gel with additionalingredients. This document broadly covers the use of nearly any dilatantgel composition including a wide range of additional ingredients thatmay act as particulate matter in the gel. Also, see column 3, lines22-25 in which the gel can be a polysaccharide, and an additional“thickener” can be starch, see column 4, lines 27-2.

This invention relates to a plastic modeling composition of a softpliable, working consistency for being molded into any desired shape orform and is slow-drying so as to be retained in a workable moldablecondition for a long period of time to be repeatedly reworked and moldedinto different shapes and forms. It particularly pertains to a modelingcomposition for children's play, and is clean, non-sticky andnon-staining

SUMMARY OF THE INVENTION

One of the main objects of the invention is a modeling composition whichmay be reworked and remolded, or may be used for modeling objects whichare more or less permanent. Another object of the invention is amodeling composition which is easily compounded and another object ofthe invention is a modeling composition which is efficient in use.

Another object of the invention is a modeling composition which isnon-toxic

Another object of the invention is a modeling composition in whichadditives such as colorants, texturants, odorants, flavorants and thelike different colors may be incorporated. However care should be takenthat the quantity of such additives do not affect its moldableconsistency or shelf life.

The compositions may be molded into objects adapted to be painted withconventional water and oil based paints

Further objects, and objects relating to details of construction andcomposition, will readily appear from the detailed description tofollow. The objects of the invention have been accomplished by the meansset forth in the following specification. The invention is clearlydefined and pointed out in the appended claims; example compositions arealso set forth for carrying out the invention. Generally described theinvention comprises a composition consisting essentially of vegetableflour, such as grain flour which is adapted to be gelatinized and wateronly although other ingredients may be added as will appear below.

There is provided a process for the formation of an adhesive shearthickening dilatant fluid comprising adding to a starch gel, asufficient portion of dry non toxic solid material to form a kneadablesolid.

Suitably there is provided a process for the formation of an adhesiveshear thickening dilatant fluid comprising adding to a starch gel, asufficient portion of uncooked starch to form a kneadable solid. In sucha process it has been found suitable to use an aqueous based starch geland as the added starch dry uncooked starch. Any starch may be used forthis purpose including but not limited to wheat starch, potato starch,rice starch and tapioca starch. However it is preferred to use cornstarch most suitably waxy corn starch containing high levels ofamylopectin, most desirably at least 90% by weight of amylopectin.

Any starch gel prepared by any method may be used. Commerciallyavailable starch gels are generally satisfactory. The gels may beprepared by methods well known in the art either in ambient temperaturesolvents or heated solvents generally water, but not limited thereto.

One embodiment of the of the present invention is the provision of ashear thickening dilatant fluid and a process for the formation thereofcomprising the sequential steps of forming a gel comprising a firstportion of starch and water and adding a sufficient second portion of adry non toxic solid material, suitably a dry starch to said gel to forma kneadable solid which is dry to the touch.

Suitably, the second portion of solid material is corn starch althoughother very finely divided materials may also be viable.

Suitably the process comprises swelling said first portion of starch inwater to a temperature sufficient to form said gel, allowing the saidthus formed gel to cool to ambient temperature, mixing said secondportion of starch with said gel and applying sufficient pressure to saidmixture to form a kneadable solid.

The nature of the starch is not critical, however it has been founduseful to utilize corn starch, preferably waxy maize starch which isprincipally amylopectin most suitably containing at least 90% preferably99% by weight of amylopectin, as the starch. The use of high or pureamylopectin and the absence of amylose enhances the shelf life of theproduct.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Where a pregelatinized or cold water swelling starch is used as thefirst starch it will form a gel at ambient temperatures. No substantialamount of heating such as boiling is needed

It is desirable that the process comprises combining at least threeparts by weight of starch with each 100 parts by weight of water to forma gel and adding to each 100 parts by weight of gel from about 50 toabout 150 parts by weight of dry uncooked starch. In particular thereshould be employed 5 to 10 parts by weight of starch with each 100 partsby weight of water to form the gel and adding to each 100 parts byweight of gel, from about 67 to about 133 parts by weight of dry starch.

Most suitably, there are combined 5 to 10 parts by weight of starch witheach 100 parts by weight of water to form the gel and there are added toeach 100 parts by weight of gel from about 60 to about 80 parts byweight of dry starch.

There may be added other components to improve the quality of the finalproduct. These qualities include strength, flexibility, non-stickiness,stretchability and shelf life.

The quality of the dilatant fluid produced by this process may beenhanced by the use of one or more additive materials selected from thegroup consisting of a humectant, such as glycerin, a lipid, suitably alow acid oil, such as canola oil, a non toxic salt, suitably a salt of astrong acid such as sodium or potassium chloride and the like and boraxsaid additive material being a component of at least one member of thegroup consisting of the starch gel and the added starch. The designationof such additives is merely illustrative and not limiting.

The best shelf life is provided by the use of amylopectin as both of thestarch components. Use of amylopectin in an air tight container willprovide a shelf life of several months or more. Addition of a humectant,including but not limited to glycerin, provides an extended usable timeoutside of a sealed container.

The addition of antimicrobial agents is also helpful. These need not beof a complex or sophisticated nature. Most non toxic salts of strongbases and strong acids will be adequate. Common salt or sodium chloridemay be readily employed.

In order to improve the stretchability of the final product, borax hasbeen found useful. The addition of lipids or vegetable oils, suitablylow acid vegetable oils such as canola oil is useful to improve thesmoothness of the product and is helpful in avoidance of the productsticking to the hands.

Any or all of these quality enhancing components may be used. Theamounts employed will vary with the nature and quantities of the starchused in the basic material and the effect desired. There is no absolutelimitation as to the amount of such components which can be added.Nevertheless it has been found useful to limit the total weight of theseadditional components to about 15% by weight of the final productcontaining them.

EXAMPLES Example 1

Very fluid material, unstable due to syneresis within two weeks.

Wet component: Water 200 g Cornstarch (not modified, about 25% amylose,75%  10 g amylopectin) emulsifying wax flakes  2 g (polysorbate 60 &cetearyl alcohol) dimethicone (polymethylsiloxane)  1 g Dry ComponentCornstarch (not modified, about 25% amylose, 75% 250 g amylopectin)Baking Soda 260 g

Wet component ingredients were combined and heated to 100° C. whilestirring gently. After the liquid thickened, it was removed from theheat source and allowed to cool to room temperature. Thereafter the dryingredients were added and stirred gently to combine.

Example 2

Very fluid material, unstable due to syneresis within two weeks.

Wet component: Water 100 g  Tapioca Starch 5 g Psyllium HydrophilicMucilloid powder 5 g Dry Component Cornstarch (not modified, about 25%amylose, 75% 37 g  amylopectin) Borax 4 g

Wet component ingredients were combined and heated to 100° C. whilestirring gently. After the liquid thickened, it was removed from theheat source and allowed to cool to room temperature. Thereafter the dryingredients were added and stirred gently to combine

Example 3

Reasonably good putty, unstable due to syneresis within two weeks.

Wet component: Water 100 g  Tapioca starch 5 g Dry Component Cornstarch(not modified, about 25% amylose, 75% 57 g  amylopectin) Borax 4 g

Wet component ingredients were combined and heated to 100° C. whilestirring gently. After the liquid thickened, it was removed from theheat source and allowed to cool to room temperature. Thereafter the dryingredients were added and stirred gently to combine

Example 4

Reasonably good putty, unstable due to syneresis within two weeks.

Wet component: Water 400 g Cornstarch (not modified, about 25% amylose,75%  36 g amylopectin) Borax  9 g NaCl salt  4 g Dry ComponentCornstarch (not modified, about 25% amylose, 75% 250 g amylopectin) PalmOil  15 g

Wet component ingredients were combined and heated to 100° C. whilestirring gently. After the liquid thickened, it was removed from theheat source and allowed to cool to room temperature. Thereafter the dryingredients were added and stirred and kneaded to combine.

Example 5

Not as soft or stretchy as desired, unstable due to syneresis within twoweeks.

Wet component: Water 50 g Wheat flour  7 g Borax  9 g Dry ComponentCornstarch (not modified, about 25% amylose, 75% 30 g amylopectin)

Wet component ingredients were combined and heated to 100° C. whilestirring gently. After the liquid thickened, it was removed from theheat source and allowed to cool to room temperature. Thereafter the dryingredients were added and stirred and kneaded to combine.

Example 6

Good shelf life, good material qualities, requires cooking.

Wet component: Water 186 g  ThermFlo modified corn starch, 99%Amylopectin, mfg by 21 g Ingredion Borax 12 g NaCl Salt 18 g DryComponent ThermFlo modified corn starch, 99% Amylopectin, mfg by 135 g Ingredion Canola oil 16 g

Wet component ingredients were combined and heated to 100° C. whilestirring gently. After the liquid thickened, it was removed from theheat source and allowed to cool to room temperature. Thereafter the dryingredients were added and stirred and kneaded to combine.

Example 7

Excellent shelf life, excellent material qualities, no cooking required.

Wet component: Water (warm) 1260 g  UltraTex SR, cold water swellingmodified corn starch, 162 g 99% Amylopectin, mfg by Ingredion Borax  72g NaCl salt 108 g Glycerin 120 g Dry Component ThermTex modified cornstarch, 99% Amylopectin, mfg 930 g by Ingredion Canola Oil  90 gGlycerin  40 g

Combine wet components and allow setting as a gel, adding dry componentstirring gently, and then kneading mixture, stopping when materialbecomes smooth and forms a cohesive mass.

Glycerin acts as a humectant delaying drying out. Borax increases crosslinking of starch gel, and thus material stability. Salt contributes toantimicrobial property. Canola is a low acid oil that reduces stickinesswithout damaging starch gel stability.

Example 8

Cornstarch and water only ingredients, lasts only minutes before dryingout. Material that results is not shelf stable due to retrogradation ofthe starch gel.

Wet component: Water 418 g Cornstarch (not modified, about 25% amylose,75%  22 g amylopectin) Dry Component Cornstarch (not modified, about 25%amylose, 75% 560 g amylopectin)

Wet component ingredients were combined and heated to 100° C. whilestirring gently. After the liquid thickened, it was removed from theheat source and allowed to cool to room temperature. Thereafter the dryingredients were added and stirred and kneaded to combine.

Example 9

Material is stable, but prone to drying out easily.

Wet component: Water 418 g UltraTex SR (Ingredion) cold water swellingwaxy maize  22 g modified food starch (99% + Amylopectin) Dry ComponentThermTex (Ingredion) uncooked waxy maize modified food 560 g starch(99% + Amylopectin)

Modified cornstarch and water are the only ingredients, cooking notrequired. The wet components were combined and allowed to set as a gel,dry component added while stirring gently, then the mixture was kneaded,stopping when material become smooth and formed a cohesive mass

Example 10

Material that results is not shelf stable due to retrogradation of thestarch gel. Cornstarch and water are the only ingredients. The materiallasts only minutes before drying out.

Wet component: Water 418 g Cornstarch (not modified, about 25% amylose,75%  22 g amylopectin) Dry Component 56% ThermTex (Ingredion) uncookedwaxy maize 560 g modified food starch (99% + Amylopectin)

Wet component ingredients were combined and heated to 100° C. whilestirring gently, after the liquid thickened, it was removed from theheat source and allowed to cool to room temperature. Thereafter the dryingredients were added and stirred and kneaded to combine.

Example 11

Very stable material results.

Wet component: Water 4529 g  Borax, finely divided solid 259 g NaClsalt, finely divided solid 388 g Glycerin 431 g UltraTex SR (Ingredion)cold water swelling waxy maize 582 g modified food starch (99% +Amylopectin) Dry Component ThermTex (Ingredion) uncooked waxy maizemodified 3343 g  food starch Canola 324 g Glycerin 144 g

Wet components were mixed with water at ambient The wet components werecombined stirred and allowed to set as a gel in about 10 minutes, drycomponent added while stirring gently, then the mixture was kneaded,stopping when material become smooth and formed a cohesive mass

Glycerin acts as a humectant, delaying drying out. Borax increases crosslinking of starch gel, and thus material stability. Salt contributes toantimicrobial property. Canola is a low acid oil that reduces stickinesswithout damaging starch gel stability.

Example 12

High-quality material results. Stability highly variable, and limited bytype of starch used in gel.

Wet component: Water 4529 g  Borax, finely divided solid 259 g NaClsalt, finely divided solid 388 g Glycerin 431 g Starch: any type ofstarch, or any combination of modified 582 g or unmodified starches(Rice, Potato, Tapioca, Corn, etc.) Dry Component Starch: any type ofstarch, or any combination of modified 3343 g  or unmodified starches(Rice, Potato, Tapioca, Corn, etc.) Canola 324 g Glycerin 144 g

All wet non starch components are mixed into water heated to 37° C. Mixin starch, stirring slowly, cook if required to form gel, heating toabout 100° C. depending on starch type as starch begins to gel, allowsetting for 10 minutes. Then add dry components stirring gently, kneadmixture, stopping when material becomes smooth and forms a cohesivemass.

Glycerin acts as a humectant, delaying drying out. Borax increases crosslinking of starch gel, and thus material stability. Salt contributes toantimicrobial property. Canola is a low acid oil that reduces stickinesswithout damaging starch gel stability. Glycerin, borax, salt and canolaare each optional, and may be used in any combination independent ofeach other.

Example 13

Material of fair quality. Stability highly variable, dependent on starchused.

Wet component: Water 4762 g Starch: any type of starch, or anycombination of modified  238 g or unmodified starches (Rice, Potato,Tapioca, Corn, etc.) Dry Component Starch: any type of starch, or anycombination of modified 5000 g or unmodified starches (Rice, Potato,Tapioca, Corn, etc.)

Cook wet components if required to form gel, heating to about 100° C.depending on starch type. Stir slowly as starch begins to gel, allow toset 10 minutes and reach room temperature. Add dry component stirringgently, then knead mixture, stopping when material becomes smooth andforms a cohesive mass.

Example. 14

Gel made with less starch. Material of variable quality and stability,dependent on starch used.

Wet component: Water 5882 g Starch: any type of starch, or anycombination of modified  176 g or unmodified starches (Rice, Potato,Tapioca, Corn, etc.) Dry Component Starch: any type of starch, or anycombination of modified 3942 g or unmodified starches (Rice, Potato,Tapioca, Corn, etc.)

Cook wet components if required to form gel, heating to about 100° C.depending on starch type. Stir slowly as starch begins to gel, allow toset 10 minutes and reach room temperature. Add dry component stirringgently, then knead mixture, stopping when material becomes smooth andforms a cohesive mass.

Example 15

Prepared in accordance with U.S. Pat. No. 6,713,624

Wet component: Water 500 g Starch: Wheat flour 400 g High AmylopectinCorn Starch 100 gMixed all ingredients and heated slightly while mixing, to simulate heatgenerated by larger batch mixed for 5 minutes as illustrated in theHasbro patent. All starch in the mixture gelatinized and resultantmaterial was not significantly different in texture and materialproperties from any number of well known play dough materials.

Example. 16

Gel made with more starch. Material of variable quality and stability,dependent on starch used.

Wet component: Water 4115 g Starch: any type of starch, or anycombination of modified  412 g or unmodified starches (Rice, Potato,Tapioca, Corn, etc.) Dry Component Starch: any type of starch, or anycombination of modified 5473 g or unmodified starches (Rice, Potato,Tapioca, Corn, etc.)

Cook wet components if required to form gel, heating to about 100° C.depending on starch type. Stir slowly as starch begins to gel, allow toset for 10 minutes and reach room temperature. Add dry componentstirring gently, then knead mixture, stopping when material becomessmooth and forms a cohesive mass.

In accordance with any of the foregoing procedures, in place of creatingthe initial gel there may be used starch gel, and this is commonly knownto persons skilled in the art, which may be made using “cold waterswelling (CWS)” or “cook up” starch. CWS starch does not require heatingto form a gel with water, cook up starch does require heating. Heatingtemperature and duration required to gel “cook up” starches in watervaries by type of starch, and may be affected by other additives such assalt.

I claim:
 1. A process for the formation of an adhesive shear thickeningdilatant fluid comprising adding to a starch gel, a sufficient portionof dry non toxic solid material to form a kneadable solid.
 2. A processfor the formation of an adhesive shear thickening dilatant fluidcomprising adding to a starch gel, a sufficient portion of uncookedstarch to form a kneadable solid.
 3. The process of claim 2 wherein theadded starch. Is dry uncooked starch.
 4. The process of claim 3 whereinthe starch gel is an aqueous based starch gel.
 5. The process of claim 2wherein the added starch is corn starch.
 6. The process of claim 5wherein the corn starch is principally amylopectin.
 7. The process ofclaim 6 where said corn starch comprises at least 90% by weight ofamylopectin.
 8. The process of claim 3 or 6 which comprises utilizing aninitial starch gel containing at least three parts by weight of starchwith each 100 parts by weight of water and adding to each 100 parts byweight of gel from about 50 to about 150 parts by weight of dry starch.9. The process of claim 8 which comprises utilizing an initial starchgel containing about 5 to about 10 parts by weight of starch with each100 parts by weight of water and adding to each 100 parts by weight ofgel from about 67 to about 133 parts by weight of dry starch.
 10. Theprocess of claim 8 which comprises utilizing an initial starch gelcontaining combining about 10 to about 15 parts by weight of starch witheach 100 parts by weight of water and adding to each 100 parts by weightof gel from about 60 to about 80 parts by weight of dry starch.
 11. Theprocess of claim 2 additionally comprising as an additive material, atleast one member selected from the group consisting of a humectant, alipid, a non toxic salt, and borax said additive material being acomponent of at least one member of the group consisting of the starchgel and the added starch.
 12. The dilatant material of claim 11 whereinsaid additive material comprises up to about 15% by weight of the entiredilatant material.
 13. The process of claim 11 wherein said additivematerial at least comprises a salt of a strong acid.
 14. The process ofclaim 11 wherein the said additive material at least comprises borax.15. The process of claim 11 wherein the said additive material at leastcomprises a lipid.
 16. The process of claim 15 wherein the said lipid isa low acid oil.
 17. The process of claim 16 wherein the oil is canolaoil.
 18. The process of claim 11 wherein the humectant is glycerin. 19.The process of claim 13 wherein the salt is sodium chloride
 20. Anadhesive shear thickening dilatant fluid material produced by theprocess of claim
 2. 21. The dilatant material of claim 20 additionallycomprising as an additive material, at least one member selected fromthe group consisting of a humectant, a lipid, a non toxic salt, andborax.
 22. The dilatant material of claim 21 wherein said additivematerial comprises up to about 15% by weight of the entire dilatantmaterial.